DESCRIPTION: (Applicant's Abstract) The overall objective of the proposed research is to contribute to our understanding of risk and protective factors predicting three stages of cigarette smoking in adolescents and young adults: smoking initiation, regular cigarette use, and smoking cessation. The primary focus of this research will be on associations among these three stages and comorbid psychiatric disorders in both the adolescents/young adults and their first-degree relatives. We will also examine the contribution of psychosocial variables and familial factors as they relate to the three stages of cigarette smoking. The first aim of the study is to: identify the association of psychiatric disorders with smoking initiation, progression to regular use, and cessation among adolescents and young adults. Given a significant association, temporal order patterns will be determined. Whether the particular patterns of comorbid psychiatric disorders predict a more pernicious course of cigarette use will also be studied. Our samples provide adequate numbers to examine these questions with (a) major depressive disorder, (b) substance use disorders, (c) disruptive behavior disorders, and (d) anxiety disorders. The second aim is to: Identify the degree to which psychosocial factors, family smoking, and family psychopathology are related to smoking initiation, regular use, and cessation in adolescents and young adults. Assuming a significant univariate association, evaluate the degree to which these associations remain significant after controlling for adolescent psychopathology. The most salient risk and protective factors for a negative outcome in each of the three smoking stages will be identified. The availability of two large, ongoing studies provides us with a unique opportunity to contribute to this literature. Specifically, we will supplement the extensive psychiatric assessment of participants in the Oregon Adolescent Depression Project (OADP) and their first degree relatives to obtain more detailed information on tobacco use variables. Independent variables in the proposed study will include (a) adolescent/young adult psychiatric data obtained from OADP participants at these assessment points, (b) adolescent/young adult psychosocial risk and protective factors obtained from OADP participants at repeated assessments during adolescent and young adulthood, and (c) familial smoking and psychiatric history.